Correlation between rhizosphere microbial community of Gossypium spp. and petroleum hydrocarbon degradation in the petroleum contaminated saline-alkali soil

Objective) Open out the correlation between rhizosphere microbial community of Gossypium spp. and petroleum hydrocarbon (TPH) degradation in the petroleum contaminated saline-alkali soil. (Methods) Phospholipid fatty acid (PLFA) analysis method in different growing periods (seeding, bud and boll opening season) of Gossypium spp. was used to evaluate the microbial community diversity in the soil. (Results) It was found 21 kinds of PLFAs in the soil, including bacteria (except actinomycetes) biomarkers of saturated fatty acids (SAT), fungi species biomarkers of polyunsaturated fatty acid (PUFA), actinomycetes biomarkers of middle branched saturated fatty acids (MBSAT), Gram positive (G + ) bacteria (except actinomycetes) biomarkers of terminal branched saturated fatty acids (TBSAT), Gram negative bacteria (G − ) biomarkers of monounsaturated fatty acids (MONO) and Cyclopropyl fatty acids (CYCLO). There are significant differences on microbial diversity in the rizosphere soil between the Gossypium spp. and without cotton (CK), the differences were also observed in the different growth periods. Compared with the CK, the microbial diversity increased by 100%, 83.3%, and 20.0% and biomass of soil microbes increased by 53.9%, 6.60 times, and 60.5% for seedling, bud and boll opening periods, respectively. In addition, when Gossypium spp. was grown in the petroleum contaminated saline-alkali soil, the degradation rates of total petroleum hydrocarbon (TPH) in the rhizosphere soils increased by 13.0%, 28.0% and 30.6% in seedling, bud and boll opening periods, respectively. Correlation analysis (Spearman method) was used to determine the correlation between the soil microbial community and the TPH degradation. Although the total soil microbial biomass had a low correlation with TPH degradation with a correlation coefficient |r|=0.5, whereas i15:0, a14:0, a16:0 had a high positive correlation with the correlation coefficient |r|≥0.8. (Conclusion) The study indicate that the structure and the biomass of the soil microbial community have significant changed (P<0.05) and the TPH degradation have improved in the rhizospheres soils of Gossypium spp.. The planting of Gossypium spp. can effectively improve TPH contaminated saline-alkali soil, and the results have a great reference value in application of TPH contaminated saline-alkali soil.